SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityDeferred

CVE-2026-54565

When a target HWP or HWPX file contains an extractable PrvImage, the extension returns the preview as a data URI in page-readable DOM, allowing page script to read it.

MEDIUM 4.7EPSS 0.19%

Does this matter?

Lower severity and a low EPSS score (0.19%). Track it; it rarely justifies an emergency change on its own.

Description

rhwp is an HWP viewer and editor implemented in Rust and WebAssembly. Prior to rhwp 0.7.15 and rhwp Chrome and Firefox extension 0.2.4, the browser extensions use an all-URLs host permission to detect HWP and HWPX links on visited pages, but the service workers do not validate message senders, URL schemes, or destination addresses before privileged fetches. The affected paths are rhwp-chrome/manifest.json, rhwp-chrome/content-script.js, rhwp-chrome/sw/message-router.js, rhwp-chrome/sw/thumbnail-extractor.js, rhwp-firefox/manifest.json, rhwp-firefox/content-script.js, rhwp-firefox/sw/message-router.js, and rhwp-firefox/sw/thumbnail-extractor.js. An untrusted page can make the fetch-file and extract-thumbnail handlers request localhost or private-network resources. When a target HWP or HWPX file contains an extractable PrvImage, the extension returns the preview as a data URI in page-readable DOM, allowing page script to read it. The flaw also permits internal-resource existence and port probing and extension presence or version fingerprinting. Exploitation requires a user to visit an untrusted page while the extension is enabled, and preview disclosure is limited to an extractable PrvImage. This issue is fixed in rhwp 0.7.15 and rhwp Chrome and Firefox extension 0.2.4.

CVSS 3.1
4.7 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N
EPSS
0.19% probability · 9th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-200, CWE-359, CWE-918, CWE-1385
Source
security-advisories@github.com
EPSS trend
0%3%5%26 October 2026: 0.19%26 October 202626 October 2026

EPSS 0.2% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.